Cloud Computing and Software Development

Leah Riungu-Kalliosaari

Contents• Cloud computing

– Definition, characteristics, service models, deployment models

– Benefits and disadvantages

• Cloud computing players• Developing software using the cloud

– Major cloud computing vendors– Google app engine – Amazon web services– Implications– Challenges

Definition

• Many definitions exist

• Cloud computing is the delivery of computing as a service rather than a product, whereby shared resources, software, and information are provided to computers and other devices as a utility (like the electricity grid) over a network (typically the Internet) - Wikipedia

Definition

• Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. – This cloud model is composed of five essential

characteristics, three service models, and four deployment models.

Source: The NIST definition of Cloud Computing, http://csrc.nist.gov/publications/nistpubs/800-145/SP800-145.pdf

Characteristics• On-demand self-service

– A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider.

• Broad network access. – Capabilities are available over the network and accessed through

standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, tablets, laptops, and workstations).

• Resource pooling. – The provider’s computing resources are pooled to serve multiple

consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). Examples of resources include storage, processing, memory, and network bandwidth.

Source: NIST

Characteristics

• Rapid elasticity– Capabilities can be elastically provisioned and released, in some

cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be appropriated in any quantity at any time.

• Measured service. – Cloud systems automatically control and optimize resource use

by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.

Source: NIST

Service Models• Software as a Service• The capability provided to the end user is to use the provider’s

applications running on a cloud infrastructure.– Applications

• User interface• Frontend applications e.g. Google docs, hotmail

– Application services• Web service interface• Basic or composite e.g Google maps

• The end user does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities.

• The end user might have control over limited user-specific application configuration settings.

• The end user does not care where the application is hosted, or what is the undelying operating system.

Source: NIST

Service Models• Platform as a Service

• The capability provided to the end user is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages, libraries, services, and tools supported by the provider. – Programming environment

• Programming language, libraries– Execution environment

• Runtime environment• E.g. Google App Engine

• The end user does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage.

• The end user has control over the deployed applications and possibly configuration settings for the application-hosting environment. Source: NIST

Service Models• Infrastructure as a Service

• The capability provided to the end user is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. – Infrastructure services

• Storage• Computational• Databases• Network• E.g. Google bigtable

• The end user does not manage or control the underlying cloud infrastructure.

• The end user has control over operating systems, storage, and deployed applications; and possibly limited control of selected networking components (e.g., host firewalls). Source: NIST

Management responsibilities of Cloud Service Types

Applications

Data

Runtime

Middleware

OS

Virtualization

Servers

Storage

Networking

Applications

Data

Runtime

Middleware

OS

Virtualization

Servers

Storage

Networking

Applications

Data

Runtime

Middleware

OS

Virtualization

Servers

Storage

Networking

Applications

Data

Runtime

Middleware

OS

Virtualization

Servers

Storage

Networking

On-Premise IaaS PaaS SaaS

You Manage

Managed By Vendor

Source: Chou, D., 2010 Microsoft Cloud Computing Platform

Service Models

• Human as a Service– Crowdsourcing

• Enabling collective intelligence e.g. Mechanical Turk

• Crowdsourced testing services e.g. uTest

– Information markets• Information aggregation services• Prediction of events e.g. Iowa Electronic Markets

Source: A. Lenk, M. Klems, J. Nimis, S. Tai, T. Sandholm, “What’s in the cloud: An architectural map of the cloud landscape,” In Proc. Cloud computing workshop, International Conference on Software Engineering, 2009

Source: A. Lenk, M. Klems, J. Nimis, S. Tai, T. Sandholm, “What’s in the cloud: An architectural map of the cloud landscape,” In Proc. Cloud computing workshop, International Conference on Software Engineering, 2009

Deployment Models• Private cloud

– Cloud infrastructure specifically used by users within a single organization

– May be owned, managed, and operated by the organization, a third party, or some combination of them.

– May exist on or off premises.

• Community cloud. – Cloud infrastructure used by a specific community of end users

from organizations with shared concerns (e.g., mission, security requirements, policy, and compliance considerations).

– May be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them

– May exist on or off premises.

Source: NIST

Deployment Models

• Public cloud. – Cloud infrastructure used open for use by the general public. – May be owned, managed, and operated by a business,

academic, or government organization, or some combination of them.

– It exists on the premises of the cloud provider.

• Hybrid cloud. – The cloud infrastructure used by two or more distinct cloud

infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds).

Source: NIST

Benefits• Reduced capital expenditure and

maintenance costs– IT resources are hosted in the cloud hence

reduced need for specialized hardware

• Infinite scalability• Access to global markets• Quick time to market • Business competitiveness

– Startups can compete with established corporations

Disadvantages

• Security, privacy and data integrity– Where is the data stored, who has access to the data,

who is responsible if security is compromised, or information is lost

• Lack of control– How does the business retain and maintain lack of

control

• Availability– How does the occurrence of downtime affect the

business

Cloud Players

• Cloud infrastructure service providers – raw cloud resources; IaaS

• Cloud platform service providers – resources + frameworks; PaaS

• Cloud intermediaries – help broker some aspect of raw resources and frameworks e.g. service management, load balancing etc

• Cloud application service providers – software applications; SaaS

• Cloud consumers – users of all the above

Developing Software using the Cloud

Cloud Computing Vendors

• Google - Google App Engine– Java, Python

• Amazon web services - Elastic Compute Cloud (EC2)– C#, .NET

• Microsoft - Windows Azure Platform– .Net languages, C++, Java

• Salesforce (Force.com)– Apex, Visualforce

• Many others e.g. Rackspace, VMware, Skytap, Heroku

Cloud-based Software Development • Using the cloud to develop software

– Cloud-based software i.e. SaaS– Non SaaS eg desktop applications

• Developers have access to platforms to build and host their applications

• The applications run in data centers that are managed by the platform provider

Cloud-based Software Development

• Fast development – From idea to market ready product within

weeks– Quick to market

• Agile development methods are used

• Views from a small cloud start up

Google App Engine

• Provides detailed information about the usage of the system– Dashboard: basically an administrative view– Follow real time usage e.g. CPU hours in

usage, data storage requests received etc– Error logs

Google App Engine• Authentication system based on GAE user API

– Google handles user authentication– Google stores the user info– Google handles security e.g. in case of security

breaches

• TRUST is important– Developer’s relationship with Google is based on trust– Developer makes use of the APIs based on the

provided documentation• Dos and Donts• By following the guidelines, it is hard for a developer to

breach the security. May be unless hacking is the developer’s intention.

Amazon Web Services• Three options when using EC2

• Ready built Amazon machine images for use at no additional cost– Pre-installed Linux distributions e.g. Redhat, Fedora 8– Windows servers

• Community made public Amazon machine images– If used, the developer needs to trust the person or organization

that created the machine image– It takes a lot of time going through all the details of capabilities of

the responsible server

• Build your own amazon machine eg a Linux server, deploy it as a virtual image to Amazon and use it as you like– You can publish it for others to use

Amazon Web Services

• Responsible for the physical security– Developer can know where the data is stored, the virtualization

stack, the software used to handle to data– No information about the internal operations of the data center

• Developer is responsible for some aspects of security– Similar to managing traditional servers e.g. which ports are open

or closed

• In terms of security, it is easy for a developer to compromise security– E.g. using a public Amazon machine image created by another

developer

Cloud-based Software Development: Implications

• Code base must work within the limitations of the platform e.g. with GAP, you can fetch 1000 lines at a time, there is a specified duration for how long your script can run before it is terminated

• Some open source platforms are available for use, e.g. AppScale is a copy of GAP.– Install AppScale on your local server and use it to run

your scripts– You must be aware of the limitations once you port your

code to the ”real” cloud environment

Cloud-based Software Development: Implications

• Code quality may not be optimal– Code quality vs economics – For example, if an application is set to respond within

100 milliseconds, and the code is not optimal, the platform will use more servers to meet the limit.

• Code sharing and collaborative development is likely to grow e.g supported by Github– Especially useful when it does not matter where one

is located around the globe

Cloud-based Software Development: Implications

• Physical infrastructure and bandwidth are availed by the cloud provider, the developer only needs to use and pay

• Pay-as-you-go pricing could result in unplanned expenditure e.g. if have a bug in your code and you enter an eternal loop

• Scaling abilities are in-built within the platform– Instructions are provided on how to enable automated scaling– Performance testing is likely to become critical in the future– Code optimization helps to prevent using too many resources

(server instances) especially when the application needs to scale.

Cloud-based Software Development: Implications

• Reduced need for capital investments – The required resources are available for use– Only one’s skills, time and a little bit of money

is needed– Operational costs incurred as one uses the

platform

• Encourage innovativeness– Little costs are incurred to develop an idea,

not much to loose if it does not thrive in the market

Cloud-based Software Development: Implications

• There is a level of tolerance towards errors by some cloud users– They do not expect the systems to be perfect,

as long as they work– They know the bugs will be fixed soon– E.g. as of November 2011, Google Apps sites

would freeze when run using internet explorer version 8

Cloud-based Software Development: Implications

• There is wide variety of potential users, so expect to run into errors even after releasing the product/service

• Security remains important– Data encryption can be used, and the

performance implications (of data encryption) need to be understood

Challenge: Security

Challenge: Interoperability

Challenge: Vendor lock-in